Studies of Rutaecarpine and Related Quinazolinocarboline Alkaloids

Article abstract of DOI:10.1021/jo00208a018

Quinazolinocarboline alkaloids, e.g., rutaecarpine (1), can readily be synthesized by treating tryptamine with 2-(trifluoromethyl)-4H-3,1-benzoxazin-4-one (quickly generated in situ from trifluoroacetic anhydride (TFAA) and 2H-3,1-benzoxazine-2,4(1H)-dione.The product formed, 3-<2-(3-indolyl)ethyl>-2-(trifluoromethyl)-4-(3H)-quinazolinone (5), is then cyclized (HCl/HOAc) to 13b-(trifluoromethyl)-13b,14-dihydrorutaecarpine (6), whereupon CF3H is eliminated by treatment with base.The sequence can conveniently be performed as a three-reaction one-pot procedure giving rutaecarpine (1) in 99percent yield within 3h.The approach can readily be extended to the synthesis of evodiamine (2), 13,13b-dehydroevodiamine (38a), and 13b,14-dihydrorutaecarpine (21).Thus treatment of 3-<2-(3-indolyl)ethyl>-4(3H)-quinazolinone (19) with TFAA affected cyclization to 13b-(trifluoroacetyl)-13b,14-dihydrorutaecarpine (20), which can be readily hydrolyzed to 13b,14-dihydrorutaecarpine (21).